Effect Analysis on Gas Control with Local High Level Gas Drainage Gateway at Initial Mining Period of Fully Mechanized Top Coal Caving Mining Face

Taking No.9801 fully mechanized top coal caving mining face in Kaiyuan Mine of Yangquan Coal Group as a study object,according to the frequent gas 0 ver limit occurred at initial mining period of fully mechanized top coal caving mining face,in combination with the deposit status and mining failure law of overburden coa I and rock strata above the coal mining face,a local high level gas drainage gateway layout plan at initial mining period of No.9801 fully mechanized top coal caving face was provided.The local high level gas drainage gateway could be divided to three sections,as inclined high level gas drainage gateway at initial mining period,strike hig h level gas drainage gateway and auxiliary inclined high level gas drainage gateway and the three sections could be linked as a gas drainage system. The inclined high I evel gas drainage gateway section at initial mining period was set at No.6 seam with a horizontal distance of 15 m to the open off cut.The strike high level gas drainage gateway section was set in No.3 seam with a vertical distance of 43 m to the coal mining face and with a distance of 4 m to air returning gateway.The site actual applica tion showed that the gas volume fraction in air returning gateway was controlled about 0.6%.The gas volume fraction in tail gateway was controlled about 1.4% and thus the gas over limit and power off problems at initial mining period of No.9801 fully mechanized top coal caving mining face were solved.